• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.402-408
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• 2002

Multicast technology allows the transmission of data from one source node to a selected group of destination nodes. Multicast routes typically use trees, called multicast routing trees, to minimize resource usage such as cost and bandwidth by sharing links. Moreover, the quality of service (QoS) is satisfied by distributing data along a path haying no more than a given number of arcs between the root node of a session and a terminal node of it in the routing tree. Thus, a multicast routing tree for a session can be represented as a hop constrained Steiner tree. In this paper, we consider the hop-constrained multicast route packing problem with bandwidth reservation. Given a set of multicast sessions, each of which has a hop limit constraint and a required bandwidth, the problem is to determine a set of multicast routing trees in an arc-capacitated network to minimize cost. We propose an integer programming formulation of the problem and an algorithm to solve it. An efficient column generation technique to solve the linear programming relaxation is proposed, and a modified cover inequality is used to strengthen the integer programming formulation.

• Journal of Communications and Networks
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• v.8 no.1
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• pp.116-122
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• 2006

Most of the multimedia applications require strict quality of service (QoS) guarantee during the communication between a single source and multiple destinations. This gives rise to the need for an efficient QoS multicast routing strategy. Determination of such QoS-based optimal multicast routes basically leads to a multi-objective optimization problem, which is computationally intractable in polynomial time due to the uncertainty of resources in Internet. This paper describes a network model for researching the routing problem and proposes a new multicast tree selection algorithm based on genetic algorithms to simultaneously optimize multiple QoS parameters. The paper mainly presents a QoS multicast routing algorithm based on genetic algorithm (QMRGA). The QMRGA can also optimize the network resources such as bandwidth and delay, and can converge to the optimal or near-optimal solution within few iterations, even for the networks environment with uncertain parameters. The incremental rate of computational cost can close to polynomial and is less than exponential rate. The performance measures of the QMRGA are evaluated using simulations. The simulation results show that this approach has fast convergence speed and high reliability. It can meet the real-time requirement in multimedia communication networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3094-3109
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• 2014

This paper proposes a load balanced reliable routing protocol called LBR (Load Balanced Reliable routing) in wireless networks. The LBR protocol transmits messages through a reliable path considering the balancing of the traffic load. Recently, the authors have proposed a multipath-based reliable routing protocol called MRFR, which is an appealing protocol for fault tolerant reliable data transmission. However, However, MRFR has no concern with the problem of load balancing, which results in increasing congestion and consuming high energy at some network nodes. As a result, the problem affects negatively the performance of the network. Taking account of load balancing as a route selection criteria can avoid routing through the congested nodes and allows to find better routes. In this paper, we extend MRFR by considering load balancing in the route discovery process of reliable communication. The simulation results showed that the proposed protocol outperforms AODV in terms of end-to-end delay, packet delivery radio, and average jitter. Compared to MRFR, the LBR protocol has the same packet delivery ratio, and obtains a better efficiency of load balancing.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1731-1737
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• 2007

This paper considers subway routing problem. Given a schedule of train to be routed by a railway stock, the routing problem determines a sequence of trains while satisfying turnaround time and maintenance restrictions. Generally, the solution of routing problem is generated from set partition formulation solved by column generation method, a typical integer programming approach for train-set. However, we find the characteristics of metropolitan subway which has a simple rail network, a few end stations and 13 departure-arrival patterns. We reflect a turn-around constraint due to spatial limitations has no existence in conventional railroad. Our objective is to minimize the number of daily train-sets. In this paper, we develop two basic techniques that solve the subway routing problem in a reasonable time. In first stage, we formulate the routing problem as a Min-cost-flow problem. Then, in the second stage, we attempt to normalize the distance covered to each routes and reduce the travel distance using our heuristic approach. Applied to the current daily timetable, we could find the subway routings, which is an approximately 14% improvement on the number of train-sets reducing 15% of maximum traveling distance and 8% of the standard deviation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.469-472
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• 2008

Hierarchical routing in Wireless Sensor Network lowers the amount of a memory used and energy consumption so that the network lifetime longer. But, When Node Failure is occurred, Hierarchical routing do not look for another route. This is the problem of Hierarchical routing. To solve the problem, we would study other hierarchical routings. There are typically hierarchical routing protocols which can be used in WSN, such as the hierarchical routing of Zigbee and HiLow protocol which is submitted as draft to IETF 6LoWPAN WG. Also, there is SCRO algorithm which be able to assign short-cut routing path. This paper explains how to solve the Node Failure in each Zigbee hierarchical routing and HiLow protocol. And we suggest how to solve the Node Failure in SCRO protocol. SCRO protocol is able to assign new routing path rapidly when Node Failure is occurred. Because the strong of SCRO protocol is to assign Short-cut routing path.

• Convergence Security Journal
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• v.11 no.1
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• pp.11-18
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• 2011

Wireless mesh network technology with transmission speeds similar to wired and wireless technology means to build, compared with wired networks, building a more efficient network to provide convenience and flexibility. The wireless mesh network router nodes in the energy impact of the mobility is less constrained and has fewer features entail. However, the characteristics of various kinds due to network configuration settings and the choice of multiple paths that can occur when the system overhead and there are many details that must be considered. Therefore, according to the characteristics of these network routing technology that is reflected in the design and optimization of the network is worth noting. In this paper, a multi-path setting can be raised in order to respond effectively to the problem of the router node data loss and bandwidth according to traffic conditions and links to elements of the hop count evaluation by using a genetic algorithm as a workaround for dynamic routing the routing metric for wireless mesh network scheme is proposed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.475-478
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• 2004

Tool costs can comprise a significant part of the total operating costs of Flexible Manufacturing Systems. We address the problem of determining the optimal processing times of individual operations and routing mix in FMSs with multiple routes for each part type in order to minimize tool cost, subject to meeting a throughput constraint for each part type. The problem is formulated as a nonlinear program superimposed on a closed queueing network of the FMSs under consideration. Numerical examples reveal the potential of our approach for significant saving in tool costs.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.4
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• pp.328-337
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• 2004

Tool costs can comprise a significant part of the total operating costs of Flexible Manufacturing Systems. We address the problem of determining the optimal processing times of individual operations and routing mix in FMSs with multiple routes for each part type in order to minimize tool cost, subject to meeting a throughput constraint for each part type. The problem is formulated as a nonlinear program superimposed on a closed queueing network of the FMSs under consideration. Numerical examples reveal the potential of our approach for significant saving in tool costs.

• International Journal of Computer Science & Network Security
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• v.23 no.8
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• pp.85-90
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• 2023

The Ant Colony System (ACS) is a variant of Ant colony optimization algorithm which is well-known in Traveling Salesman Problem. This paper proposed a hybrid method based on genetic algorithm (GA) and ant colony system (ACS), called GACS, to solve traffic routing problem. In the GACS, we use genetic algorithm to optimize the ACS parameters that aims to attain the shortest trips and time through new functions to help the ants to update global and local pheromones. Our experiments are performed by the GACS framework which is developed from VANETsim with the ability of real map loading from open street map project, and updating traffic light in real-time. The obtained results show that our framework acquired higher performance than A-Star and classical ACS algorithms in terms of length of the best global tour and the time for trip.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.62-66
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• 2008

In this paper we have proposed a power aware location based routing protocol for wireless ad hoc network. The existing greedy perimeter stateless routing (GPSR) has some problems which are certain node overloaded and void situation. The proposed power aware greedy perimeter stateless routing (PAGPSR) protocol gives a solution for these problems in GPSR. PAGPSR uses power aware and geographically informed neighbor selection to route a packet towards the destination. It also gives a solution for the fundamental problem in geographical routing called communication void. It considers residual energy of battery and distance to the destination for the next hope node selection. When it encounters a void it starts limited-flooding to select next hop node. To evaluate the performance of our protocol we simulated PAGPSR in ns-2. Our simulation results show that our protocol achieves longer network lifetime compared with greedy perimeter stateless routing (GPSR).